Display device and electronic apparatus
A display device able to amplify the same input as a power supply voltage of IC by using low temperature polysilicon having high threshold voltage and large variation and an electronic apparatus using the same, including MCK use level shifters 171 - 1 and 171 - 2 of a type where a reset operation is periodically necessary, a logic circuit 173 for using a level shift horizontal synchronization signal Hsync to input reset pulses for the MCK level shifters 171 - 1 and 171 - 2 having a period of N horizontal periods shifted in phase by M horizontal periods (note, M<N) to the level shifters 171 - 1 and 171 - 2 and outputting the resultant signals, and a function of selecting the circuit not performing the reset operation among outputs of the L number of level shifters 171 - 1 and 171 - 2 for each M horizontal periods and outputting a level shift master clock LSMCK as a last output signal.
1. An integral drive circuit type display device supplied with at least a master clock, comprising a level conversion circuit for converting a first level at a time of input of said master clock to a second level of an internal drive voltage level and outputting a level shifted master clock to a predetermined circuit, wherein
said level conversion circuit includes
L number of level shifters configured to perform a reset operation periodically,
a logic circuit for inputting reset pulses to said level shifters having a period of N horizontal periods shifted by M horizontal periods (where M<N) based on a level shifted horizontal synchronization signal Hsync, and selecting a circuit not performing the reset operation among the outputs of the L number of level shifters for the M horizontal periods to output the level shifted master clock.
2. A display device as set forth in claim 1 , wherein said level shifter comprises
an inverter connected between said internal drive voltage level potential and a reference potential,
a first node,
a second node connected to an input of said inverter,
a third node connected to an output of said inverter,
a capacitor connected between said first node and said second node, and
a circuit for preventing the input of said master clock for exactly a reset period, supplying an intermediate potential of said first level potential and reference potential to said first node, and bringing said second node and said third node into conductive states.
3. A display device as set forth in claim 2 , wherein said second node and said third node are connected by a switching transistor, and a gate potential of the switching transistor is held at a negative potential when not conductive.
4. A display device as set forth in claim 2 , wherein said inverter is connected to the negative potential in place of the reference potential.
5. An electronic apparatus having an integral drive circuit type display device supplied with at least a master clock,
wherein said display device comprises a level conversion circuit for converting a first level at a time of input of said master clock to a second level of an internal drive voltage level and outputting a level shifted master clock to a predetermined circuit, and
wherein said level conversion circuit includes
L number of level shifters configured to perform a reset operation periodically,
a logic circuit for inputting reset pulses to said level shifters having a period of N horizontal periods shifted by M horizontal periods (where M<N) based on a level shifted horizontal synchronization signal Hsync, and
selecting a circuit not performing the reset operation among the outputs of the L number of level shifters for the M horizontal periods to output the level shifted master clock.
6. An electronic apparatus as set forth in claim 5 , wherein said level shifter comprises
an inverter connected between said internal drive voltage level potential and a reference potential,
a first node,
a second node connected to an input of said inverter,
a third node connected to an output of said inverter,
a capacitor connected between said first node and said second node, and
a circuit for preventing the input of said master clock for exactly a reset period, supplying an intermediate potential of said first level potential and reference potential to said first node, and bringing said second node and said third node into conductive states.
7. An electronic apparatus as set forth in claim 6 , wherein said second node and said third node are connected by a switching transistor, and a gate potential of the switching transistor is held at a negative potential when not conductive.
8. An electronic apparatus as set forth in claim 6 , wherein said inverter is connected to the negative potential in place of the reference potential.